Jacob Cass offers some advice for freelancers in sussing out the technical savvy of potential clients and how to approach the project discovery discussion.
You may want to impress your client with the vast amount of knowledge that you have, however, if they do not understand it, then all of your effort is lost. ... [W]hen explaining a concept, slow down, provide examples and talk in familiar terms.
http://justcreativedesign.com/2008/07/06/how-to-talk-to-non-tech-savvy-clients/